Marinate mushrooms in salad dressing. Heat grill pan or skillet.
Meanwhile, add all spices and garlic to 1 tablespoon of olive oil and heat. Once garlic becomes soft, add onions and salt. Cook until transparent. Add spinach and cook further until wilted.
Add remaining olive oil to grill pan and add the mushrooms. Grill for 1-2 minutes on each side. In same pan, grill rolls. Optional: Brush vegan bread with olive oil before grilling.
Spread Nayonnaise on one half of the vegan bread. On the other half, place cheese, mushroom and onion mixture. Close the sandwich and enjoy! Tastes great with baked sweet potato fries.